Possibility for calendar to include tasks/reminders

I have been moving over from Disroot, which uses Nextcloud, to mailbox. I am uncertain if I will move over yet for my calendar and reminders, because I like to have them in the same calendar 'stream'(?!). In Nextcloud/Disroot when I create a new calendar, I have the option of using the same calendar in tasks/reminders as well, which makes for better organisation (in my opinion).

I would like this option in mailbox, too (or if this is already possible I'd love to learn how to do this).